变频技术在凝结水泵上的应用

本文分析了威海电厂凝结水系统存在的能源浪费问题和变频节能原理,介绍了采用的变频器的结构和调节、运行中出现的问题及处理措施。通过节能效果分析,表明该项技术可以取得可观的经济效益,而且在电力工业中具有很好的推广价值。     

Measurement of heat transfer coefficients for steam condensation on a vertical 21.5-mm-O.D. tube in the presence of air

ABSTRACT

Governing the rate of heat transport by condenser tubes in the passive containment cooling system (PCCS), the steam condensation over a vertical cylinder in the presence of air was investigated experimentally. The main objective of this study was to explore if the condensation heat transfer coefficient relies on the tube dimension, which has been a variable missed in most condensation models or has been embraced without experimental demonstration under phase change environments. The mean heat transfer coefficient was measured in the condensation test facility named JERICHO (JNU Experimental Rig for Investigation of Condensation Heat transfer On tube). The outer diameter of the condenser tube used in this study was set to 21.5 mm. The measured heat transfer coefficients were compared to those obtained from the 40-mm-O.D. tube, and a multiplier to correct the variation of the heat transfer coefficient with the tube diameter was proposed for its application to Lee correlation. The proposed correlation was further validated against another set of experimental data obtained from a separate test facility housing the 31.8-mm-O.D. tube.     

Bio‐Based,Self‐Condensed Polyols

A new method for the synthesis of high‐molar‐mass (MM), bio‐based polyols for elastic polyurethanes is developed. This process is based on the self‐condensation of low MM polyols (M_n ≈ 1000) and vacuum removal of the resulting glycerol. Self‐condensation products are hyperbranched estolide polyols with average MMs close to 3000 and hydroxyl numbers in the range of 40–95 mg KOH g^?1. Three polyols, one with primary and two with secondary hydroxyls and different functionalities, are studied. The transesterification proceeded much faster with primary hydroxyls, leading to high‐viscosity products. The effect of functionality and reactivity of starting polyols on properties is discussed. Practical applications: The process is useful for upgrading the existing natural oil‐based polyols to higher MM, lower OH number and variable‐functionality polyols, for expanding application in the urethane field. The process is simple, involving just an oil‐based polyol, a catalyst, and heating under vacuum.     

含不凝性气体蒸汽浸没射流冷凝压力振荡实验研究

实验研究了不凝性气体（空气）含量、水温和蒸汽质量流速对蒸汽浸没射流冷凝压力振荡特性的影响,实验工况横跨冷凝振荡（CO）区和稳定冷凝（SC）区。结果表明：对于纯蒸汽射流,压力振荡主频随水温的升高而降低,振荡强度随水温的升高而升高;在CO区,振荡主频和振荡强度均随蒸汽质量流速的升高而升高;在SC区,振荡主频随蒸汽质量流速的升高而降低,振荡强度基本上不随蒸汽质量流速的变化而发生改变;对于含空气射流,随空气质量分数的增加,振荡主频总体呈下降趋势,振荡强度先迅速下降后小幅上升,在空气质量分数为0.05～0.1区域内振荡主频和振荡强度均存在极小值。     

烘缸虹吸器的选型与应用

论述了纸机烘缸虹吸器的应用情况，解释了在不同车速下选用虹吸器应注意的事项，同时也分析了烘缸内冷凝水的状态，以便更好地理解虹吸器的应用原理。     

几种新型吡啶腙类Schiff碱配体的合成

分别以6-溴吡啶-2-甲酸和3-腈基-4-甲基-2,6-二氯吡啶为原料,经过酰胺化、肼取代、缩合等反应合成4种新型吡啶腙类Schiff碱有机配体:N-苯基-2-甲酰胺-6-肼吡啶缩水杨醛;N-苯基-2-甲酰胺-6-肼吡啶缩香草醛;N-苯基-2-甲酰胺-6-肼吡啶缩对羟基苯甲醛;3-腈基-4-甲基-2,6-二肼吡啶二缩水杨醛。通过红外光谱、核磁共振谱对其结构进行了表征。     

邻硝基苯磺酰基—N—乙基替苯胺的制备

本文主要介绍了由邻硝基氯苯，N－乙基苯胺等为基本原料经过醚化，氯化，缩合等反应合成邻硝基苯磺酰基乙基替苯胺的方法，论述了合成工艺及反应条件对产品产率的影响，介绍了其在化工生产中的应用。     

Aldol condensation of acetaldehyde to form high molecular weight compounds on TiO2

Temperature-programmed desorption, hydrogenation, and oxidation are used to show that acetaldehyde undergoes continued aldol condensation beyond crotonaldehyde formation on Degussa P-25 titania to form hexan-2,4-diene-al and higher molecular weight compounds containing conjugated C=C bonds. Aromatic compounds also form, and at higher temperatures coke forms. Degussa P-25 TiO₂ has more sites that catalyze chain propagation reactions beyond formation of C₄ species than do pure anatase or rutile surfaces. These reactions may be responsible for deactivation observed during photocatalytic oxidation of acetaldehyde at elevated temperatures. This revised version was published online in August 2006 with corrections to the Cover Date.     

WSA-DC——下一代高浓度高转化率WSA工艺

介绍了托普索公司新开发的WSA-DC工艺,详述其流程、优点、性能、消耗和生产数据.WSA-DC工艺是一个两次冷凝工艺,它结合了WSA工艺与两转两吸工艺的优点,通过对中间冷凝器的设计改进和仔细控制气体中的H2O/SO2比率,可以用ψ(SO2)等于或高于13%的原料气生产w(H2SO4)为99%的硫酸.以1套540t/d硫磺制酸装置为例,对WSA-DC工艺和传统干法两转两吸工艺进行了技术经济比较.     

精炼脱臭中冷冻水真空系统和乙二醇型“干冰”冷凝真空系统的技术经济分析

介绍了冷冻水真空系统和乙二醇型"干冰"冷凝真空系统的工作原理及工艺特点,并进行了技术性能对比。对两种真空系统应用在不同规模精炼脱臭生产线的经济效益进行了对比,分析了两者的适用范围。结果表明:冷冻水真空系统更适用于中、小规模油脂精炼脱臭真空系统,乙二醇型"干冰"冷凝真空系统更适用于大、中规模油脂精炼脱臭真空系统。